Norway’s prime minister has said its military will be more visible at oil and gas installations as politicians across Europe warned the suspected sabotaging of the two Nord Stream pipelines could herald a new stage of hybrid warfare targeting vulnerable energy infrastructure in order to undermine support of Ukraine. Jonas Gahr Støre told a news conference Norway would step up its military presence at Norwegian installations after the country had become Europe’s largest supplier of natural gas. He added that any attack on the Nato member’s offshore installations would be handled jointly with its allies. Large amounts of natural gas have been pouring into the Baltic Sea since Monday through three separate leaks on the two Nord Stream pipelines built to deliver Russian gas to Europe. Seismologists recorded explosions in the Swedish and Danish waters where the pipeline passes the island of Bornholm on Monday morning and evening, suggesting the leaks were deliberate. The Latvian foreign minister, Edgars Rinkēvičs, posted to social media that it “seems we enter a new phase of hybrid war”, without naming who he believed was responsible. “Sabotage on Nord Stream I and II pipelines must be classified as most serious security and environmental incident in the Baltic Sea,” he added. The German defence minister, Christine Lambrecht, said: “The presumed act of sabotage on the Baltic Sea pipelines has again made clear how reliant we are on critical infrastructure – including that below water.” However, she urged caution on identifying the culprits while investigations are being undertaken. Oppositions politicians in Germany were more forthright. Roderich Kiesewetter, a member of parliament for the conservative Christian Democratic Union (CDU), told the Guardian the pipeline attack had the hallmarks of the “hybrid warfare approach” Russia has pursued for the last decade, with the aim of “dividing the European Union not by military but through social and diplomatic means”. “We have to ask who has an interest in destroying this infrastructure,” said Kiesewetter, a member of the Bundestag’s committee on foreign affairs. While it was in the interest of the US, states in central and eastern Europe and the Baltics that Nord Stream 2 would never be activated, he argued that an act of state-sponsored sabotage by a Nato ally would have come attached with too large a risk of a political backlash. “Russia, on the other hand, has an interest in sending us a signal: to threaten it could cause similar damage to pipelines between Algeria and France, to our power lines or submarine fibre-optic cables […] I consider it likely that Russia was behind this attack.” The Kremlin has dismissed descriptions of the Nord Stream leaks as a Russian “terrorist attack” as “stupid and absurd”. Foreign ministry spokeswoman Maria Zakharova on Wednesday said Russia intends to call a UN security council meeting over damage to two Nord Stream undersea gas pipelines. Norway has expressed concern about a number of recent sightings of unidentified drones or aircraft inside the safety exclusion zones that surround oil and gas facilities. Its energy minister, Terje Aasland, said on Tuesday that Oslo was coordinating with the Norwegian armed forces, police, and oil and gas industry operators on security issues. Gassco, the Norwegian state-owned pipeline operator that runs about 9,000 kilometres of gas infrastructure, said it was sharing information with Danish and Swedish authorities about the Nord Stream incident. “We have already reviewed and stepped up our security measures since the start of the war in Ukraine,” said its senior vice-president for system operation, Alfred Skår Hansen. “Our pipelines are built to last a hundred years plus and withstand tremendous force, so you would need high levels of competence to do actual damage.” Germany’s interior minister on Wednesday said the country must prepare for previously “unimaginable” threats to its energy security after the pipeline leaks. “We have to adapt to scenarios that were previously unimaginable,” Nancy Faeser said. “That requires strong security authorities with the necessary resources and powers.” Nord Stream has been at the heart of a standoff between Russia and Europe over energy supplies since the start of the Kremlin’s war in Ukraine, but it is not immediately clear who stands to benefit from the destruction of the gas infrastructure. Nord Stream 2, a project driven along by German governments for years in spite of warnings from its easterly neighbours, was halted by the chancellor, Olaf Scholz, shortly before the start of the war and has never transported any gas to Germany. While there have been calls from political parties on the far right and the far left to open the pipeline as an energy crisis looms over Europe this autumn, a German U-turn on the subject in the imminent future is highly unlikely under the current balance of political power in the country, even while the pipeline remained intact. Nord Stream 1, through which a significant amount of European gas demands was met until spring this year, was gradually throttled by the Russian state-owned gas giant Gazprom and has not carried any gas to Germany since the start of September. “This attack, if it was one, did not have any direct impact on the gas market, simply because there wasn’t any gas flowing through the pipelines at the time”, said Lion Hirth, a professor of energy policy at the Hertie School, a private university in Berlin. “Gazprom has played the monopoly game with gas prices over the last year and a half, but that game is practically over, because it already reduced flows to near-zero.” “But we should be clear that any damage to energy infrastructure in Europe that is in use – offshore pipelines from Norway, gas fields, LNG terminals – would have an immediate and devastating impact on security of energy supply. There is just no buffer at the moment when it comes to gas”. “If it were to be established that Russia was prepared to go as far as destroying pipelines it part-owns, then the question is where it is willing to go next”, Hirth said. “And that’s a very worrying thought.” US intelligence this summer warned the German government of a possible attack on gas pipelines in the Baltic, Der Spiegel reported earlier. Citing sources familiar with the subject, the news magazine said the CIA had issued such a warning only a few weeks ago. The European Union has threatened to retaliate with sanctions to what it believes was likely a “deliberate act” of sabotage against the Nord Stream infrastructure in the Baltic Sea. Speaking on behalf of the 27 member states, the EU foreign policy chief said on Tuesday that the leaks from two Russia-Germany undersea gas pipelines this week were “not a coincidence” and would be answered with a “robust and joint reaction”.